This invention relates to a carton blank and carton for packaging and dispensing a printing blanket, and more particularly to a method of using a carton which permits the alignment and controlled feeding of a metal-backed printing blanket onto a rotating print cylinder of a printing press.
The most common commercial printing process is offset lithography. In this printing process, ink is offset from a printing plate to a rubber blanket mounted on a cylinder before being transferred to a substrate, such as paper. Typically, the cylinder comprises a metal cylinder having an encircling rubber printing blanket which is releasably mounted to the cylinder. The rubber printing blanket may be reinforced with either a cloth back or a metal back. Unlike the cloth back, the metal back adds durability to the carried rubber layer(s) on the blanket by removing stress which occurs from tensioning the printing blanket as it is mounted on the metal cylinder.
However, with a cloth back the printing blanket may be rolled upon removal from its shipping carton and maintained as a roll by finger pressure. This minimal amount of handling pressure permits two operators to easily align the blanket in a locking device which is typically located in a longitudinal gap in the metal cylinder. Additionally, as the cylinder rotates to mount the blanket thereon, the operators can easily control the tension and alignment of the unrolling blanket with such minimal handling pressure.
With a metal-backed printing blanket, the metal sheet strongly desires to uncoil upon removal from a conventional shipping carton. The handling pressure needed to maintain the metal-backed blanket as a coil makes it difficult for the operators to properly insert and align the blanket into the locking device of the cylinder. Additionally, the resistance of the blanket to being coiled makes it difficult to control the tension and alignment of the blanket as it unrolls onto the rotating cylinder. Such problems have resulted in a high percentage of ruined metal-backed blankets due to improper installation.
Accordingly, there is a need in the printing industry for an improved procedure or device which maintains the coiled condition of the blanket and permits the dispensing of a metal-backed printing blanket to a print cylinder in a controlled fashion.